Pair of General Electric 6SN7GTB Vacuum Tubes – Dual Triode
For analog audio enthusiasts and vintage electronics restorers, replacing vacuum tubes is a critical step in maintaining peak performance. We proudly offer this Pair of General Electric 6SN7GTB Vacuum Tubes, an excellent opportunity to acquire fully functional replacements from one of the golden eras of American electronics.
Condición y Pruebas Técnicas
Es fundamental destacar la transparencia en la condición de este artículo. Este set se vende como par, pero no es un matched pair (no han sido emparejados por transconductancia o ganancia). Las válvulas han sido sometidas a pruebas de diagnóstico utilizando un probador de tubos Kyoritsu K-119 (como se evidencia en la documentación fotográfica), superando con éxito las pruebas de emisión básica (marcando en el rango “Good” / “OK”). Físicamente, presentan marcas de General Electric (logos en cristal y base), confirmando su linaje vintage, acompañadas de empaques de la marca.
Manufacturer History: General Electric (GE)
General Electric (GE) was one of the undisputed leaders in vacuum tube manufacturing in the United States. From the 1940s through the 1980s, GE produced millions of thermionic valves for military, industrial, and consumer applications. Following the acquisition of Ken-Rad, GE’s Kentucky manufacturing facilities became renowned for producing some of the company’s finest vacuum tubes. Today, these tubes are highly regarded for their rugged construction, exceptional durability, and distinctive sonic character, offering deep, controlled bass and clean, detailed highs. They remain a preferred choice among audiophiles and vintage electronics enthusiasts over many contemporary European and Russian alternatives.
Primary Uses and Applications
The 6SN7GTB is a medium-mu dual triode vacuum tube. The “GTB” designation indicates a glass envelope (Glass Tube) with enhanced specifications, including higher maximum plate voltage ratings and controlled heater warm-up characteristics. Its most common applications include:
Hi-Fi Audio: Ideal for line-stage preamplifiers and tube headphone amplifiers (e.g., Schiit Freya and DarkVoice 336SE).
Instrument Amplification: Ideal for use as phase inverters in vintage guitar amplifiers.
Restoration Projects: Suitable for restoring vintage radios and television receivers that require EIA 8B or 8BD specification tubes.
Technical Specifications (Datasheet Overview)
For technicians, engineers, and DIY builders, below are the nominal operating specifications of the 6SN7GTB vacuum tube family:
Type: Medium-Mu Twin Triode.
Base: 8-Pin Octal (JEDEC 8BD).
Filament Volt (Heater): 6.3 Volts AC/DC.
Heater Current: 0.6 A.
Maximum Plate Voltage: 450 V (The 6SN7GTB version is rated for higher maximum plate voltage than the earlier 6SN7GT models).
Maximum Plate Dissipation: 5.0 W per plate / 7.5 W total (both plates combined).
Amplification Factor (μ): 20.
Transconductance (Gm): Approximately 2,600 µmhos (at 250 V plate voltage).
(FAQ)
Q: Is this Pair of General Electric 6SN7GTB Vacuum Tubes a Matched Pair?
A: No. These tubes are sold together as a pair, but they have not been electronically matched for transconductance (Gm) or gain. They are an excellent choice for applications where precise tube matching is not required.
Q: How were these tubes tested?
A: They were tested using a classic Kyoritsu K-119 vacuum tube tester. The test performed measures electron emission only, and both tubes tested within the green “Good” (Good/OK) range, confirming satisfactory emission and proper operating condition.
Q: What is the difference between a 6SN7GT and a 6SN7GTB?
A: The 6SN7GTB (introduced in 1954) is an improved version of the original 6SN7GT. It features a higher maximum plate voltage rating (450 V versus 300 V for the GT) and a controlled heater warm-up time of approximately 11 seconds, reducing thermal stress and helping extend the tube’s service life.
Q: Are these genuine General Electric vacuum tubes?
A: The tubes are supplied in General Electric-branded boxes. As shown in the detailed product photographs, each tube features the classic General Electric logo printed on both the glass envelope and the Bakelite base, including the “Made in USA” marking, confirming their authentic American vintage manufacture.
